Wed Mar 1 20:08:42 2023 UTC ()
mremap(2): Fix example to use MAP_PRIVATE.

It is a historical accident that MAP_PRIVATE is assumed when neither
it nor MAP_SHARED is specified.

XXX pullup-9
XXX pullup-10


(riastradh)
diff -r1.7 -r1.8 src/lib/libc/sys/mremap.2
cvs diff -r1.7 -r1.8 src/lib/libc/sys/mremap.2 (expand / switch to unified diff)

--- src/lib/libc/sys/mremap.2 2018/05/03 05:09:48 1.7
+++ src/lib/libc/sys/mremap.2 2023/03/01 20:08:41 1.8
@@ -1,14 +1,14 @@ @@ -1,14 +1,14 @@
1.\" $NetBSD: mremap.2,v 1.7 2018/05/03 05:09:48 wiz Exp $ 1.\" $NetBSD: mremap.2,v 1.8 2023/03/01 20:08:41 riastradh Exp $
2.\" 2.\"
3.\" Copyright (c) 2007 Thomas Klausner and Joerg Sonnenberger 3.\" Copyright (c) 2007 Thomas Klausner and Joerg Sonnenberger
4.\" All rights reserved. 4.\" All rights reserved.
5.\" 5.\"
6.\" Redistribution and use in source and binary forms, with or without 6.\" Redistribution and use in source and binary forms, with or without
7.\" modification, are permitted provided that the following conditions 7.\" modification, are permitted provided that the following conditions
8.\" are met: 8.\" are met:
9.\" 1. Redistributions of source code must retain the above copyright 9.\" 1. Redistributions of source code must retain the above copyright
10.\" notice, this list of conditions and the following disclaimer. 10.\" notice, this list of conditions and the following disclaimer.
11.\" 2. Redistributions in binary form must reproduce the above copyright 11.\" 2. Redistributions in binary form must reproduce the above copyright
12.\" notice, this list of conditions and the following disclaimer in the 12.\" notice, this list of conditions and the following disclaimer in the
13.\" documentation and/or other materials provided with the distribution. 13.\" documentation and/or other materials provided with the distribution.
14.\" 14.\"
@@ -127,27 +127,27 @@ return_2_end(void) @@ -127,27 +127,27 @@ return_2_end(void)
127} 127}
128 128
129int 129int
130main(int argc, char *argv[]) 130main(int argc, char *argv[])
131{ 131{
132 void *maprw, *maprx; 132 void *maprw, *maprx;
133 int rv; 133 int rv;
134 size_t page = (size_t)sysconf(_SC_PAGESIZE); 134 size_t page = (size_t)sysconf(_SC_PAGESIZE);
135 135
136 // Create the first mapping that has no protections, but intended 136 // Create the first mapping that has no protections, but intended
137 // protections only 137 // protections only
138 maprw = mmap(NULL, page, 138 maprw = mmap(NULL, page,
139 PROT_MPROTECT(PROT_EXEC|PROT_WRITE|PROT_READ), 139 PROT_MPROTECT(PROT_EXEC|PROT_WRITE|PROT_READ),
140 MAP_ANON, -1, 0); 140 MAP_ANON|MAP_PRIVATE, -1, 0);
141 if (maprw == MAP_FAILED) 141 if (maprw == MAP_FAILED)
142 err(EXIT_FAILURE, "mmap failed"); 142 err(EXIT_FAILURE, "mmap failed");
143 143
144 // Create the second mapping for the same physical space, which 144 // Create the second mapping for the same physical space, which
145 // again has no protections. 145 // again has no protections.
146 maprx = mremap(maprw, page, NULL, page, MAP_REMAPDUP); 146 maprx = mremap(maprw, page, NULL, page, MAP_REMAPDUP);
147 if (maprx == MAP_FAILED) 147 if (maprx == MAP_FAILED)
148 err(EXIT_FAILURE, "mremap failed"); 148 err(EXIT_FAILURE, "mremap failed");
149 149
150 // Set the first mapping read/write 150 // Set the first mapping read/write
151 if (mprotect(maprw, page, PROT_READ|PROT_WRITE) == -1) 151 if (mprotect(maprw, page, PROT_READ|PROT_WRITE) == -1)
152 err(EXIT_FAILURE, "mprotect(rw) failed"); 152 err(EXIT_FAILURE, "mprotect(rw) failed");
153 153